A reception diversity technique, as one wireless communication technique, is in practical application in GSM (registered trademark) cellular phones and IS-95 cellular phones as 2nd generation cellular phones.
The reception diversity technique has been used in a case where mobile reception of a terrestrial digital broadcast is performed using a tuner built in the car navigation system. Patent Literature 1 discloses a conventional technique thereof.
In Patent Literature 1, two reception antennas are used. However, at present, a car navigation system with four antennas for reception diversity is in practical use.
As one spatial demultiplexing technique, MIMO (Multi Input Multi Output) technique is in practical use in 802.11n system transmitters/receivers for a wireless LAN (Local Area Network).
After this, the MIMO technique has been adopted in an LTE (Long Term Evolution) system as the 3.9th generation cellular phone system.
The LTE system as the 3.9th generation system is standardized as disclosed in Non-patent Literatures 1 to 5.